scholarly journals Palaeogeographic reconstruction of a fluvio-marine transitional system in Narmada rift basin, India — Implications on Late Cretaceous global sea-level rise

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Biplab Bhattacharya ◽  
Suparna Jha ◽  
Prantik Mondal
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
High Frequency ◽  
Depositional Environments ◽  
Systematic Change ◽  
Rift Basin ◽  
Facies Association ◽  
Facies Associations ◽  
Sandstone Formation ◽  
Global Sea Level

AbstractRising sea-levels in tectonically active epicontinental basins often lead to varied depositional settings and palaeogeography, mostly influenced by the net accommodation resulting from mutual interference of the extent and nature of landward encroachment by the sea and the net sedimentation. The Cenomanian Nimar Sandstone Formation, Bagh Group, Narmada rift basin, uniquely portrays the effect of sea-level rise within an intra-cratonic setting and attributes to the corresponding palaeogeographic changes in west-central India. An integrated sedimentological–sequence-stratigraphic study of the broadly fining-upward Nimar Sandstone Formation (thickness ~ 20–30 m) depicts the actual nature of changeover from a fluvial to a marine-dominated transitional depositional setting. Detailed sedimentological study reveals total seventeen facies, grouped in five facies associations, viz., the channel-fill facies association (FA-1), the overbank facies association (FA-2), the fluvial-dominated fluvio-tidal facies association (FA-3), the tide-dominated fluvio-tidal facies association (FA-4), and the shoreface facies association (FA-5). Overall facies architecture indicates a west-to-eastward marine encroachment, resulting in stacking of three distinct palaeo-depositional conditions: (i) an initial fluvial system with channel and overbank, changing into a tide-influenced fluvial bay-head delta in the inner estuary, followed by (ii) marine encroachment leading to a tide-dominated central estuary with inter- to sub-tidal settings, and finally, (iii) with further intense marine encroachments, a wave-reworked open shore condition in the outer estuary zone. The overall fining-up succession with a systematic change from fluvial to marine-dominated depositional systems points to a landward shift of the shoreline, signifying a major transgressive event correlated to the Cenomanian global sea-level rise. Characteristic stratal stacking patterns point to four coarsening- and fining-up hemicycles, embedded within the major transgressive succession. These high-frequency cycles attest to the varied interplay of sedimentation, tectonics and sea-level changes, and the resultant net accommodations. A palaeogeographic model is proposed based on the high-frequency transgressive–regressive hemicycles, which envisages the evolution of the depositional environments in relation to the Cenomanian eustatic rise in the intra-cratonic riftogenic fluvio-marine transitional basinal setup.

scholarly journals Famennian glaciation in the eastern side of Parnaíba Basin, Brazil: evidence of advance and retreat of glacier in Cabeças Formation

2015 ◽  
Vol 45 (suppl 1) ◽  
pp. 13-27 ◽  
Author(s):  
Roberto Cesar de Mendonça Barbosa ◽  
Afonso César Rodrigues Nogueira ◽  
Fábio Henrique Garcia Domingos
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
High Energy ◽  
Normal Faults ◽  
Facies Association ◽  
Delta Front ◽  
Cross Bedding ◽  
Facies Associations ◽  
Detachment Surface ◽  
Parnaíba Basin

ABSTRACTGlaciotectonic features studied in the siliciclastic deposits of Cabeças Formation, Upper Devonian, represent the first evidence of Famennian glaciation in Southeastern Parnaíba Basin, Brazil. Outcrop-based stratigraphic and facies analyses combined with geometric-structural studies of these deposits allowed defining three facies association (FA). They represent the advance-retreat cycle of a glacier. There are: delta front facies association (FA1) composed of massive mudstone, sigmoidal, medium-grained sandstone with cross-bedding and massive conglomerate organized in coarsening- and thickening-upward cycles; subglacial facies association (FA2) with massive, pebbly diamictite (sandstone, mudstone and volcanic pebbles) and deformational features, such as intraformational breccia, clastic dikes and sills of diamictite, folds, thrust and normal faults, sandstone pods and detachment surface; and melt-out delta front facies associations (FA3), which include massive or bedded (sigmoidal cross-bedding or parallel bedding) sandstones. Three depositional phases can be indicated to Cabeças Formation: installation of a delta system (FA1) supplied by uplifted areas in the Southeastern border of the basin; coastal glacier advance causing tangential substrate shearing and erosion (FA1) in the subglacial zone (FA2), thus developing detachment surface, disruption and rotation of sand beds or pods immersed in a diamicton; and retreat of glaciers accompanied by relative sea level-rise, installation of a high-energy melt-out delta (FA3) and unloading due to ice retreat that generates normal faults, mass landslide, folding and injection dykes and sills. The continuous sea-level rise led to the deposition of fine-grained strata of Longá Formation in the offshore/shoreface transition in the Early Carboniferous.

scholarly journals Reply to ‘Waves do not contribute to global sea-level rise’

2018 ◽  
Vol 9 (1) ◽  
pp. 3-3 ◽  
Author(s):  
Angélique Melet ◽  
Benoît Meyssignac ◽  
Rafaël Almar ◽  
Gonéri Le Cozannet
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Global Sea Level

scholarly journals Greenland ice sheet contribution to sea level rise during the last interglacial period: a modelling study driven and constrained by ice core data

2013 ◽  
Vol 9 (1) ◽  
pp. 353-366 ◽  
Author(s):  
A. Quiquet ◽  
C. Ritz ◽  
H. J. Punge ◽  
D. Salas y Mélia
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Core ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Interglacial Period ◽  
Last Interglacial ◽  
Intergovernmental Panel ◽  
Orbital Configuration ◽  
Global Sea Level

Abstract. As pointed out by the forth assessment report of the Intergovernmental Panel on Climate Change, IPCC-AR4 (Meehl et al., 2007), the contribution of the two major ice sheets, Antarctica and Greenland, to global sea level rise, is a subject of key importance for the scientific community. By the end of the next century, a 3–5 °C warming is expected in Greenland. Similar temperatures in this region were reached during the last interglacial (LIG) period, 130–115 ka BP, due to a change in orbital configuration rather than to an anthropogenic forcing. Ice core evidence suggests that the Greenland ice sheet (GIS) survived this warm period, but great uncertainties remain about the total Greenland ice reduction during the LIG. Here we perform long-term simulations of the GIS using an improved ice sheet model. Both the methodologies chosen to reconstruct palaeoclimate and to calibrate the model are strongly based on proxy data. We suggest a relatively low contribution to LIG sea level rise from Greenland melting, ranging from 0.7 to 1.5 m of sea level equivalent, contrasting with previous studies. Our results suggest an important contribution of the Antarctic ice sheet to the LIG highstand.

Greenland ice sheet hydrology

2013 ◽  
Vol 38 (1) ◽  
pp. 19-54 ◽  
Author(s):  
Vena W. Chu
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Field Studies ◽  
Ice Dynamics ◽  
Surface Water Hydrology ◽  
Basal Sliding ◽  
Hydrologic System ◽  
Global Sea Level

Understanding Greenland ice sheet (GrIS) hydrology is essential for evaluating response of ice dynamics to a warming climate and future contributions to global sea level rise. Recently observed increases in temperature and melt extent over the GrIS have prompted numerous remote sensing, modeling, and field studies gauging the response of the ice sheet and outlet glaciers to increasing meltwater input, providing a quickly growing body of literature describing seasonal and annual development of the GrIS hydrologic system. This system is characterized by supraglacial streams and lakes that drain through moulins, providing an influx of meltwater into englacial and subglacial environments that increases basal sliding speeds of outlet glaciers in the short term. However, englacial and subglacial drainage systems may adjust to efficiently drain increased meltwater without significant changes to ice dynamics over seasonal and annual scales. Both proglacial rivers originating from land-terminating glaciers and subglacial conduits under marine-terminating glaciers represent direct meltwater outputs in the form of fjord sediment plumes, visible in remotely sensed imagery. This review provides the current state of knowledge on GrIS surface water hydrology, following ice sheet surface meltwater production and transport via supra-, en-, sub-, and proglacial processes to final meltwater export to the ocean. With continued efforts targeting both process-level and systems analysis of the hydrologic system, the larger picture of how future changes in Greenland hydrology will affect ice sheet glacier dynamics and ultimately global sea level rise can be advanced.

scholarly journals Decadal-scale onset and termination of Antarctic ice-mass loss during the last deglaciation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Michael E. Weber ◽  
Nicholas R. Golledge ◽  
Chris J. Fogwill ◽  
Chris S. M. Turney ◽  
Zoë A. Thomas
Keyword(s):  
Mass Loss ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ross Sea ◽  
Ice Sheet ◽  
Rate Of Change ◽  
Last Deglaciation ◽  
Decadal Scale ◽  
Ice Sheet Modeling ◽  
Global Sea Level

AbstractEmerging ice-sheet modeling suggests once initiated, retreat of the Antarctic Ice Sheet (AIS) can continue for centuries. Unfortunately, the short observational record cannot resolve the tipping points, rate of change, and timescale of responses. Iceberg-rafted debris data from Iceberg Alley identify eight retreat phases after the Last Glacial Maximum that each destabilized the AIS within a decade, contributing to global sea-level rise for centuries to a millennium, which subsequently re-stabilized equally rapidly. This dynamic response of the AIS is supported by (i) a West Antarctic blue ice record of ice-elevation drawdown >600 m during three such retreat events related to globally recognized deglacial meltwater pulses, (ii) step-wise retreat up to 400 km across the Ross Sea shelf, (iii) independent ice sheet modeling, and (iv) tipping point analysis. Our findings are consistent with a growing body of evidence suggesting the recent acceleration of AIS mass loss may mark the beginning of a prolonged period of ice sheet retreat and substantial global sea level rise.

scholarly journals Rising Sea Level, Receding Boundaries and Freezing Baselines in a Warming Climate

2019 ◽  
pp. 1-7
Author(s):  
Emojong Amai Mercy ◽  
Eliud Garry Michura
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Sea Level ◽  
Future Climate Change ◽  
Maritime Boundary ◽  
Climate Change Effect ◽  
Global Sea Level ◽  
Comprehensive Framework ◽  
Maritime Boundary Delimitation ◽  
International Boundaries

This paper discusses the less publicised but far from less significant, an issue of how the international community’s approach to maritime boundary delimitation will be impacted by climate change resulting in sea level rise with coastal lands submerging affecting the international boundaries and impacting on biodiversity and human survival in the future. The climate change effect is already creating pressure on international law regardless of the direction that the law of the sea takes in remedying this dilemma. It is quite apparent that global disputes and conflicts are arising and solutions are needed urgently. The climate change and the consequent global sea level rise are widely touted to submerge islands and coastlines without discrimination. The international community has been relatively slow to react to what could pose an unprecedented threat to human civilisation.  The policies that have been applied have arguably been reactive and not proactive.  In future climate change may develop other by-products which may not be understood at this moment and may require a proactive approach. Further discussion of the merits of the potential paths is ideal in ensuring that appropriate and well thought-out resolutions are negotiated. Regardless of the outcome, the thorough debate is required to ensure the correct decision is made and that the balancing act between fulfilling states' interests and achieving a meaningful result does not become detrimental to the solidity and the enforceability of the outcome. There is a need to establish a comprehensive framework for ocean governance for management and long-term development and sustainability.

scholarly journals Reconstruction of the depositional sedimentary environment of Oligocene deposits (Qom Formation) in the Qom Basin (northern Tethyan seaway), Iran

Geologos ◽  
2020 ◽  
Vol 26 (2) ◽  
pp. 93-111
Author(s):  
Amrollah Safari ◽  
Hossein Ghanbarloo ◽  
Parisa Mansoury ◽  
Mehran Mohammadian Esfahani
Keyword(s):  
Sea Level ◽  
Sedimentary Environment ◽  
Depositional Environments ◽  
Sea Level Changes ◽  
Third Order ◽  
Depositional Sequences ◽  
Qom Formation ◽  
Tethyan Seaway ◽  
Qom Basin ◽  
Global Sea Level

AbstractDuring the Rupelian–Chattian, the Qom Basin (northern seaway basin) was located between the Paratethys in the north and the southern Tethyan seaway in the south. The Oligocene deposits (Qom Formation) in the Qom Basin have been interpreted for a reconstruction of environmental conditions during deposition, as well as of the influence of local fault activities and global sea level changes expressed within the basin. We have also investigated connections between the Qom Basin and adjacent basins. Seven microfacies types have been distinguished in the former. These microfacies formed within three major depositional environments, i.e., restricted lagoon, open lagoon and open marine. Strata of the Qom Formation are suggested to have been formed in an open-shelf system. In addition, the deepening and shallowing patterns noted within the microfacies suggest the presence of three third-order sequences in the Bijegan area and two third-order depositional sequences and an incomplete depositional sequence in the Naragh area. Our analysis suggests that, during the Rupelian and Chattian stages, the depositional sequences of the Qom Basin were influenced primarily by local tectonics, while global sea level changes had a greater impact on the southern Tethyan seaway and Paratethys basins. The depositional basins of the Tethyan seaway (southern Tethyan seaway, Paratethys Basin and Qom Basin) were probably related during the Burdigalian to Langhian and early Serravallian.

Fossil shorelines at Corfu and surrounding islands deduced from erosional notches

The Holocene ◽  
2014 ◽  
Vol 24 (11) ◽  
pp. 1565-1572 ◽  
Author(s):  
Niki Evelpidou ◽  
Anna Karkani ◽  
Paolo A Pirazzoli
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Vertical Movements ◽  
Northeastern Part ◽  
Vertical Displacements ◽  
Global Sea Level ◽  
Tectonic Movements

New geomorphological investigations along the coasts of Corfu, Othonoi, Paxoi, and Antipaxoi Islands allowed the identification of recent fossil shorelines. Former sea-level positions were deduced from sea-level indicators. A ‘modern’ tidal notch, submerged c. −20 cm, was observed in all studied islands. This notch is regarded to have been submerged by the global sea-level rise that occurred during the 19th and 20th centuries at a rate exceeding the possibilities of intertidal bioerosion. Its presence provides evidence that no vertical tectonic movements occurred since its formation. On Corfu, impacts of ancient earthquakes have left some marks of emergence at about ≥+130 ± 11, +110 ± 11, +65 ± 11, +40 ± 11, and +25 ± 11 cm, as well as marks of submergence at about −40 to −50, −85 ± 11, −120 ± 11, and −180 ± 11 cm. The emergence of +130 ± 11 cm, previously dated at about 790–400 cal. bc, was detected through erosion notches at various sites in the western part of Corfu and appears to continue even more west, at Othonoi Island. Tidal notches submerged at depths exceeding 0.4 m were observed in the northeastern part of the island and suggest the local occurrence of a sequence of four coseismic subsidences, with average vertical displacements of 40 cm, during at least the last few millennia. At Paxoi and Antipaxoi, Holocene vertical movements seem to have been mainly of subsidence. At Paxoi, the ‘modern’ notch was found at about −20 to −30 cm, while four more submerged tidal notches were distinguished at about −40 ± 11, −60 ± 11, −75 ± 11, and −90 ± 11 cm, while in Antipaxoi, three submerged tidal notches were distinguished at about −60 ± 11, −75 ± 11, and −120 ± 11 cm.

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